Is there a possibility to get this information without loading the complete html code of the site? If one wants to get the resolution of a few videos at once, it seems to be a relevant efficiency overhead.
– jakob.jMay 14 '15 at 16:01

Following on from Isra's solution.
Yes it does seem that youtube hasn't developed their oEmbed API code as the videoFrameSize returns 470 x 270 px.
But least it gives you something to GRAB hold of dynamically!

Using the suck it ans see method that 'Lee taylor' put forward is a KISS way of achieving this, but not ideal if you need a dynamic content.

OK - bearing in mind the inaccurate dimensions provided by oEmbed - it does provide a solution.

I am currently developing a strusturedData generator for video content on a gallery all linked to youTube videos.

Here is an inaccurate way of getting a Dimension from youtube, but least its data!

It does not work. If i upload a video that is 300x250 px i get: {"type":"video","html":"\u003ciframe .... "height":344,"width":459...} No where does it say 300x250, and 459x344 is not the same proportion (width/height ratio) as 300x250
– Jakob SternbergMar 9 '17 at 14:15